Functional near infrared spectroscopy (fNIRS) was used to assess cortical hemodynamics and neural connectivity in adults who do and do not stutter during fluent and disfluent speech. fNIRS data was acquired using a Hitachi ETG-4000 two-probe system as seven adults who stutter and seven adults who do not stutter made phone calls. We asked, does the fNIRS signal during stuttered and fluent speech differ significantly in cortical regions that are known to be activated during speaking? Also, are there differences in hemodynamic response functions between adults who stutter (AWS) and adults who do not stutter (AWNS)? Finally, we asked whether there were group differences in the functional connectivity of the hemodynamic response function among five regions of interest (ROI): inferior frontal cortex, superior temporal cortex, inferior parietal lobule, primary motor cortex, and supplementary motor cortex). Area under the curve (AUC) analyses of the oxygenated and deoxygenated hemodynamic response function concentration values were compared for fluent and stuttered speech in each group across five ROIs. There were significant ROI main effects for both oxy and deoxy AUC analyses, and significant region x task and task x group interactions. Granger Causality analyses revealed stronger networks between supplementary motor cortex and primary motor cortex for adults who did not stutter as compared to adults who stutter. Taken together, these results suggest that multiple aspects of cortical hemodynamics and neural connectivity differ between individuals who do and do not stutter, whether they are speaking fluently or stuttering.